Abstract
A chemical spray pyrolysis method has been applied to grow high Tc Y-Ba-Cu-O thin films on SiO 2 , (001)SrTiO 3 and (001)MgO substrates. The best results were obtained for films deposited on (001)SrTiO 3 and (001)MgO substrates with Tc onset at 95 and 82 and Tc zero at 82 and 76 K, respectively. For films deposited on MgO, X-ray diffraction pattern revealed that the films are highly preferentially oriented with respect to MgO substrates with the C-axis parallel to the normal of the substrate surface. Both planview and cross-sectional transmission electron microscopy have been applied to characterize the 6pitaxia1 films. The orientation relationships between the epitaxial films and the substrate were analyzed to be [001]YBCO//[001]MgO and (110)YBCO//(200)MgO. Twins, which may be preceived as domains that are rotated 900 along the C-axis of the thin films with respect to the substrate, were found to be copiously present. © 1988 Elsevier Science Publishers B.V.